io.c: warn old write

* io.c (rb_io_puts): warn if write method accepts just one
  argument.  [ruby-core:83529] [Feature #14042]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60423 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 16 insertions, 0 deletions

diff --git a/test/ruby/test_io.rb b/test/ruby/test_io.rb
index a32369eca5..f16573682b 100644
--- a/test/ruby/test_io.rb
+++ b/test/ruby/test_io.rb
@@ -2458,6 +2458,22 @@ End
     end)
   end
 
+  def test_puts_old_write
+    capture = String.new
+    def capture.write(str)
+      self << str
+    end
+
+    capture.clear
+    assert_warning(/[.#]write is outdated/) do
+      stdout, $stdout = $stdout, capture
+      puts "hey"
+    ensure
+      $stdout = stdout
+    end
+    assert_equal("hey\n", capture)
+  end
+
   def test_display
     pipe(proc do |w|
       "foo".display(w)